Abstract: The article takes the multiple fractures of the tail rotor elastomeric bearing mounting bolts made of 1Cr17Ni3A material in a certain type of aircraft as an example. In order to identify the cause of the failure, macroscopic observation, macroscopic and microscopic observation of the fracture surface, manual opening of the fracture surface observation, hardness testing, and metallographic structure observation were conducted on the faulty parts. The results showed that the fracture property of the bolt was tempering brittleness, and the tempering brittleness range of 1Cr17Ni3A martensitic stainless steel was 380～600 ℃. The analysis and investigation of the cause of the failure showed that the premature fracture of the bolt was due to the unreasonable process method formulated by the heat treatment standard, and the material’s tempering brittleness caused the bolt to fracture. An analysis was conducted on the impact of bolt fracture, and disposal measures were identified, effectively resolving external faults.